Inability to update my name on my tax records as the middle name field cannot be left blank

I have changed my name via deed poll and am currently trying to update the relevant information on my tax returns through https://www.tax.service.gov.uk/digital-forms/form/notification-of-a-change-in-personal-details/, however the site makes me unable to do this as I've dropped the middle names when changing my name. Is there a way I can register a change to say that there should be no middle name anymore? If I go forward and say NO that surely isn't properly reflective on my information but I cannot progress with YES

Hi Hannah Duffin,

If it is not letting you do this online you will need to call our helpline or write to us
Income Tax: general enquiries

Thank you.